Fan reverse maintenance mode of a climate management system

ABSTRACT

A climate management system includes a conditioning unit having a reversible fan and an enclosure. The enclosure separates an inner space of the enclosure from an external environment while allowing air flow therethrough. The reversible fan is configured to be turned by a fan motor in a first circumferential direction to pull air from the external environment into the inner space of the enclosure. The climate management system includes a monitoring system configured to monitor operational characteristics of the climate management system, and to communicate data feedback corresponding to the operational characteristics. The climate management system includes a controller configured to instruct, based on analysis of the data feedback, the fan motor to turn in a second circumferential direction opposite to the first circumferential direction to push air from the inner space into the external environment.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 62/699,550, filed Jul. 17, 2018, entitled “FAN REVERSE MAINTENANCE MODE OF A CLIMATE MANAGEMENT SYSTEM,” the disclosure of which is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to heating, ventilation, and air conditioning (HVAC) systems and, more particularly, to maintenance of the HVAC system.

A wide range of applications exist for HVAC systems. For example, residential, light commercial, commercial, and industrial systems are used to control temperatures and air quality in residences and buildings. Generally, HVAC systems may circulate a fluid, such as a refrigerant, through a closed loop between an evaporator coil where the fluid absorbs heat and a condenser where the fluid releases heat. The fluid flowing within the closed loop may be generally formulated to undergo phase changes within the normal operating temperatures and pressures of the system, so that quantities of heat can be exchanged by virtue of the latent heat of vaporization of the fluid. Fans may blow air over the coils of the heat exchangers in order to condition the air and/or refrigerant. As the coil(s) and adjacent elements receive the air flow from the fan(s), contaminants in the air flow may reduce an efficiency of the HVAC system. It is now recognized that improved maintenance of the HVAC system is desired.

SUMMARY

The present disclosure relates to a climate management system having a conditioning unit, where the conditioning unit includes a reversible fan and an enclosure. The enclosure separates an inner space of the enclosure from an external environment while allowing air flow therethrough. The reversible fan is configured to be turned by a fan motor in a first circumferential direction to pull air from the external environment into the inner space of the enclosure. The climate management system includes a monitoring system configured to monitor operational characteristics of the climate management system, and to communicate data feedback corresponding to the operational characteristics. The climate management system includes a controller configured to instruct, based on analysis of the data feedback, the fan motor to turn in a second circumferential direction opposite to the first circumferential direction to push air from the inner space into the external environment.

The present disclosure also relates to a control system of a climate management system. The control system includes a monitoring system configured to monitor operational characteristics of the climate management system, and to communicate data feedback corresponding to the operational characteristics. The control system also includes a controller configured to receive the data feedback from the monitoring system, and to instruct, based on analysis of the data feedback, a fan motor to turn fan blades of a reversible fan of a conditioning unit of the climate management system in a circumferential maintenance direction opposite to a circumferential operating direction so as to push air from an inner space within an enclosure of the conditioning unit into an external environment surrounding the enclosure.

The present disclosure also relates to a stationary outdoor unit of a heating, ventilation, and air conditioning (HVAC) system. The stationary outdoor unit includes a reversible fan having fan blades configured to be turned by a fan motor in a circumferential operating direction and in a circumferential maintenance direction opposite to the circumferential operating direction. The stationary outdoor unit also includes an enclosure which separates an inner space of the enclosure from an external environment while allowing air flow therethrough. The stationary outdoor unit also includes a monitoring system configured to monitor operational characteristics of the HVAC system, and to communicate data feedback corresponding to the operational characteristics. The stationary outdoor unit also includes a controller configured to receive the data feedback from the monitoring system, and to instruct, based on an analysis of the data feedback, the fan motor to turn the fan blades of the reversible fan in the circumferential maintenance direction so as to push air from the inner space into the external environment.

DRAWINGS

FIG. 1 is a perspective view a heating, ventilation, and air conditioning (HVAC) system for building environmental management, in accordance with embodiments described herein;

FIG. 2 is a perspective view of the packaged HVAC unit of the HVAC system of FIG. 1, in accordance with embodiments described herein;

FIG. 3 is a perspective view of a residential HVAC system, in accordance with embodiments described herein;

FIG. 4 is a schematic diagram of a vapor compression system that may be used in the packaged HVAC system of FIG. 2 and the residential HVAC system of FIG. 3, in accordance with embodiments described herein;

FIG. 5 is a cutaway perspective view of a stationary outdoor unit of an HVAC system, in accordance with embodiments described herein;

FIG. 6 is a cutaway perspective view of the stationary outdoor unit of FIG. 5 in a fan reverse maintenance mode, in accordance with embodiments described herein;

FIG. 7 is a schematic illustration of a split HVAC system having a stationary outdoor unit configured to operate with a normal operating mode and a fan reverse maintenance mode, in accordance with embodiments described herein;

FIG. 8 is a flow diagram illustrating a fan reverse maintenance mode of a stationary outdoor unit, in accordance with embodiments described herein;

FIG. 9 is a flow diagram illustrating a fan reverse maintenance mode of a stationary outdoor unit, in accordance with embodiments described herein;

FIG. 10 is a flow diagram illustrating a fan reverse maintenance mode of a stationary outdoor unit, in accordance with embodiments described herein;

FIG. 11 is a flow diagram illustrating a fan reverse maintenance mode of a stationary outdoor unit, in accordance with embodiments described herein; and

FIG. 12 is a flow diagram illustrating a fan reverse maintenance mode of a stationary outdoor unit, in accordance with embodiments described herein.

DETAILED DESCRIPTION

The present disclosure is directed toward heating, ventilation, and air conditioning (HVAC) systems and, more particularly, toward maintenance of an HVAC system.

A wide range of applications exist for HVAC systems. For example, residential, light commercial, commercial, and industrial systems are used to control temperatures and air quality in residences and buildings. Generally, HVAC systems may circulate a fluid, such as a refrigerant, through a closed loop between an evaporator coil where the fluid absorbs heat and a condenser where the fluid releases heat. The fluid flowing within the closed loop may be generally formulated to undergo phase changes within the normal operating temperatures and pressures of the system, so that quantities of heat can be exchanged by virtue of the latent heat of vaporization of the fluid. Fans may blow air over the coils of the heat exchangers in order to condition the air and/or refrigerant. For example, in a split HVAC system, an indoor unit may include an evaporator coil where the refrigerant extracts heat from an air flow over the evaporator coil, thereby cooling the air flow. An outdoor unit may include a condenser coil over which a separate air flow passes, and the separate air flow may extract heat from the refrigerant within the condenser.

In particular, the outdoor unit may include an enclosure forming an inner space in which the condenser coil is disposed. A fan may be disposed along a side of the enclosure, and/or partially within the inner space. The enclosure may also include a grille, for example disposed in a different side of the enclosure, which separates the inner space of the enclosure from an external environment. The grille may cover or form an air intake opening of the enclosure. For example, the grille may include a lattice structure or other structure covering an air intake opening of the enclosure, which enables an air flow therethrough, and the condenser coil may be disposed adjacent to the grille such that the air flow passes over the condenser coil. The condenser coil may be disposed immediately adjacent the grille such that the condenser coil receives the air flow as it enters the enclosure. Further, the condenser coil may include fins extending between adjacent coils to enhance thermal transfer. In normal operating conditions, fan blades of the fan may be turned by a fan motor, causing the fan to pull air from the external environment, through the grille, and over the condenser coil. The air may then pass through the fan blades of the fan, causing the air to be blown from the fan back into the external environment. As the air passes over the condenser coil as previously described, the air may extract heat from the refrigerant flowing therethrough. Thus, the heat from the refrigerant is rejected to the external environment as the air flow passes from the inner space, through the fan, and into the external environment.

In accordance with the present disclosure, the fan motor may be controlled by a controller. In certain operating conditions corresponding to a fan reverse maintenance mode, the controller may instruct the fan motor to reverse a direction of the fan blades. In other words, during normal operation, the fan blades may rotate in a first circumferential operating direction. In a fan reverse maintenance mode, the fan blades may be rotated in a second circumferential maintenance direction opposite to the first circumferential operating direction.

As the fan blades rotate in the second circumferential maintenance direction, air is drawn from the external environment, through the fan blades, and into the inner space. The air is then pushed by the fan from the inner space, across the condenser coil and grille, and to the external environment. Thus, during the fan reverse maintenance mode, contaminants which aggregate on the condenser coil and/or grille may be blown away from the condenser coil and/or grille, for example into the external environment, thereby cleaning a flow path through the outdoor unit. The fan blades of the reversible fan may be designed to facilitate the above-described reversibility.

Further, the fan reverse maintenance mode may be controlled by the controller in response to one or more data feedback inputs. For example, the controller may trigger the fan reverse maintenance mode in response to a scheduling device, such as a clock, which monitors an operating period including a regularly scheduled maintenance interval. The scheduling device may trigger the fan reverse maintenance mode during the scheduled maintenance interval, for example, once per week at a specified time and for a specified duration. The maintenance interval may be scheduled once per day, once per week, once per month, or any other suitable amount of time.

Additionally or alternatively, the data feedback may be received from an air sensor or intervening communication device, where the air sensor monitors a pressure drop in the HVAC system. The air sensor may monitor a pressure drop across the condenser coil, for example, and the controller may instruct the fan reverse maintenance mode in response to the pressure drop exceeding a threshold amount. Additionally or alternatively, the data feedback may be received from an air demand device which monitors an air demand of the HVAC system. The air demand device may monitor an upcoming or current air demand from the HVAC system to a conditioned space, for example, a demand for cool air from the HVAC system to the conditioned space. Thus, if the upcoming or current air demand corresponds to operating characteristics which are incompatible with the fan reverse maintenance mode, for example, the controller may delay the fan reverse maintenance mode.

As suggested above, the controller may analyze the data feedback inputs from any of the above-described feedback devices, which may be collectively referred to as a monitoring system, including any combination thereof, and may instruct the fan reverse maintenance mode in response to the data analysis. These and other features are described in detail below with reference to the drawings.

Turning now to the drawings, FIG. 1 illustrates a heating, ventilation, and air conditioning (HVAC) system for building environmental management that may employ one or more HVAC units. In the illustrated embodiment, a building 10 is air conditioned by a system that includes an HVAC unit 12. The building 10 may be a commercial structure or a residential structure. As shown, the HVAC unit 12 is disposed on the roof of the building 10; however, the HVAC unit 12 may be located in other equipment rooms or areas adjacent the building 10. The HVAC unit 12 may be a single package unit containing other equipment, such as a blower, integrated air handler, and/or auxiliary heating unit. In other embodiments, the HVAC unit 12 may be part of a split HVAC system, such as the system shown in FIG. 3, which includes an outdoor HVAC unit 58 and an indoor HVAC unit 56.

The HVAC unit 12 is an air cooled device that implements a refrigeration cycle to provide conditioned air to the building 10. Specifically, the HVAC unit 12 may include one or more heat exchangers across which an air flow is passed to condition the air flow before the air flow is supplied to the building. In the illustrated embodiment, the HVAC unit 12 is a rooftop unit (RTU) that conditions a supply air stream, such as environmental air and/or a return air flow from the building 10. After the HVAC unit 12 conditions the air, the air is supplied to the building 10 via ductwork 14 extending throughout the building 10 from the HVAC unit 12. For example, the ductwork 14 may extend to various individual floors or other sections of the building 10. In certain embodiments, the HVAC unit 12 may be a heat pump that provides both heating and cooling to the building with one refrigeration circuit configured to operate in different modes. In other embodiments, the HVAC unit 12 may include one or more refrigeration circuits for cooling an air stream and a furnace for heating the air stream.

A control device 16, one type of which may be a thermostat, may be used to designate the temperature of the conditioned air. The control device 16 also may be used to control the flow of air through the ductwork 14. For example, the control device 16 may be used to regulate operation of one or more components of the HVAC unit 12 or other components, such as dampers and fans, within the building 10 that may control flow of air through and/or from the ductwork 14. In some embodiments, other devices may be included in the system, such as pressure and/or temperature transducers or switches that sense the temperatures and pressures of the supply air, return air, and so forth. Moreover, the control device 16 may include computer systems that are integrated with or separate from other building control or monitoring systems, and even systems that are remote from the building 10.

FIG. 2 is a perspective view of an embodiment of the HVAC unit 12. In the illustrated embodiment, the HVAC unit 12 is a single package unit that may include one or more independent refrigeration circuits and components that are tested, charged, wired, piped, and ready for installation. The HVAC unit 12 may provide a variety of heating and/or cooling functions, such as cooling only, heating only, cooling with electric heat, cooling with dehumidification, cooling with gas heat, or cooling with a heat pump. As described above, the HVAC unit 12 may directly cool and/or heat an air stream provided to the building 10 to condition a space in the building 10.

As shown in the illustrated embodiment of FIG. 2, a cabinet 24 encloses the HVAC unit 12 and provides structural support and protection to the internal components from environmental and other contaminants. In some embodiments, the cabinet 24 may be constructed of galvanized steel and insulated with aluminum foil faced insulation. Rails 26 may be joined to the bottom perimeter of the cabinet 24 and provide a foundation for the HVAC unit 12. In certain embodiments, the rails 26 may provide access for a forklift and/or overhead rigging to facilitate installation and/or removal of the HVAC unit 12. In some embodiments, the rails 26 may fit into “curbs” on the roof to enable the HVAC unit 12 to provide air to the ductwork 14 from the bottom of the HVAC unit 12 while blocking elements such as rain from leaking into the building 10.

The HVAC unit 12 includes heat exchangers 28 and 30 in fluid communication with one or more refrigeration circuits. Tubes within the heat exchangers 28 and 30 may circulate refrigerant through the heat exchangers 28 and 30. For example, the refrigerant may be R-410A. The tubes may be of various types, such as multichannel and/or microchannel tubes, conventional copper or aluminum tubing, and so forth. Together, the heat exchangers 28 and 30 may implement a thermal cycle in which the refrigerant undergoes phase changes and/or temperature changes as it flows through the heat exchangers 28 and 30 to produce heated and/or cooled air. For example, the heat exchanger 28 may function as a condenser where heat is released from the refrigerant to ambient air, and the heat exchanger 30 may function as an evaporator where the refrigerant absorbs heat to cool an air stream. In other embodiments, the HVAC unit 12 may operate in a heat pump mode where the roles of the heat exchangers 28 and 30 may be reversed. That is, the heat exchanger 28 may function as an evaporator and the heat exchanger 30 may function as a condenser. In further embodiments, the HVAC unit 12 may include a furnace for heating the air stream that is supplied to the building 10. While the illustrated embodiment of FIG. 2 shows the HVAC unit 12 having two of the heat exchangers 28 and 30, in other embodiments, the HVAC unit 12 may include one heat exchanger or more than two heat exchangers.

The heat exchanger 30 is located within a compartment 31 that separates the heat exchanger 30 from the heat exchanger 28. Fans 32 draw air from the environment through the heat exchanger 28. Air may be heated and/or cooled as the air flows through the heat exchanger 28 before being released back to the environment surrounding the rooftop unit 12. A blower assembly 34, powered by a motor 36, draws air through the heat exchanger 30 to heat or cool the air. The heated or cooled air may be directed to the building 10 by the ductwork 14, which may be connected to the HVAC unit 12. Before flowing through the heat exchanger 30, the conditioned air flows through one or more filters 38 that may remove particulates and contaminants from the air. In certain embodiments, the filters 38 may be disposed on the air intake side of the heat exchanger 30 to prevent contaminants from contacting the heat exchanger 30.

The HVAC unit 12 also may include other equipment for implementing the thermal cycle. Compressors 42 increase the pressure and temperature of the refrigerant before the refrigerant enters the heat exchanger 28. The compressors 42 may be any suitable type of compressors, such as scroll compressors, rotary compressors, screw compressors, or reciprocating compressors. In some embodiments, the compressors 42 may include a pair of hermetic direct drive compressors arranged in a dual stage configuration 44. However, in other embodiments, any number of the compressors 42 may be provided to achieve various stages of heating and/or cooling. As may be appreciated, additional equipment and devices may be included in the HVAC unit 12, such as a solid-core filter drier, a drain pan, a disconnect switch, an economizer, pressure switches, phase monitors, and humidity sensors, among other things.

The HVAC unit 12 may receive power through a terminal block 46. For example, a high voltage power source may be connected to the terminal block 46 to power the equipment. The operation of the HVAC unit 12 may be governed or regulated by a control board 48. The control board 48 may include control circuitry connected to a thermostat, sensors, and alarms. One or more of these components may be referred to herein separately or collectively as the control device 16. The control circuitry may be configured to control operation of the equipment, provide alarms, and monitor safety switches. Wiring 49 may connect the control board 48 and the terminal block 46 to the equipment of the HVAC unit 12.

FIG. 3 illustrates a residential heating and cooling system 50, also in accordance with present techniques. The residential heating and cooling system 50 may provide heated and cooled air to a residential structure, as well as provide outside air for ventilation and provide improved indoor air quality (IAQ) through devices such as ultraviolet lights and air filters. In the illustrated embodiment, the residential heating and cooling system 50 is a split HVAC system having two conditioning units, referred to herein as the indoor unit 56 and the outdoor unit 58. In general, a residence 52 conditioned by a split HVAC system may include refrigerant conduits 54 that operatively couple the indoor unit 56 to the outdoor unit 58. The indoor unit 56 may be positioned in a utility room, an attic, a basement, and so forth. The outdoor unit 58 is typically situated adjacent to a side of residence 52 and is covered by a shroud to protect the system components and to prevent leaves and other debris or contaminants from entering the unit. The refrigerant conduits 54 transfer refrigerant between the indoor unit 56 and the outdoor unit 58, typically transferring primarily liquid refrigerant in one direction and primarily vaporized refrigerant in an opposite direction.

When the system shown in FIG. 3 is operating as an air conditioner, a heat exchanger 60 in the outdoor unit 58 serves as a condenser for re-condensing vaporized refrigerant flowing from the indoor unit 56 to the outdoor unit 58 via one of the refrigerant conduits 54. In these applications, a heat exchanger 62 of the indoor unit functions as an evaporator. Specifically, the heat exchanger 62 receives liquid refrigerant, which may be expanded by an expansion device, and evaporates the refrigerant before returning it to the outdoor unit 58.

The outdoor unit 58 draws environmental air through the heat exchanger 60 using a fan 64 and expels the air above the outdoor unit 58. When operating as an air conditioner, the air is heated by the heat exchanger 60 within the outdoor unit 58 and exits the unit at a temperature higher than it entered. The indoor unit 56 includes a blower or fan 66 that directs air through or across the indoor heat exchanger 62, where the air is cooled when the system is operating in air conditioning mode. Thereafter, the air is passed through ductwork 68 that directs the air to the residence 52. The overall system operates to maintain a desired temperature as set by a system controller. When the temperature sensed inside the residence 52 is higher than the set point on the thermostat, or the set point plus a small amount, the residential heating and cooling system 50 may become operative to refrigerate additional air for circulation through the residence 52. When the temperature reaches the set point, or the set point minus a small amount, the residential heating and cooling system 50 may stop the refrigeration cycle temporarily.

The residential heating and cooling system 50 may also operate as a heat pump. When operating as a heat pump, the roles of heat exchangers 60 and 62 are reversed. That is, the heat exchanger 60 of the outdoor unit 58 will serve as an evaporator to evaporate refrigerant and thereby cool air entering the outdoor unit 58 as the air passes over the heat exchanger 60. The indoor heat exchanger 62 will receive a stream of air blown over it and will heat the air by condensing the refrigerant.

In some embodiments, the indoor unit 56 may include a furnace system 70. For example, the indoor unit 56 may include the furnace system 70 when the residential heating and cooling system 50 is not configured to operate as a heat pump. The furnace system 70 may include a burner assembly and heat exchanger, among other components, inside the indoor unit 56. Fuel is provided to the burner assembly of the furnace 70 where it is mixed with air and combusted to form combustion products. The combustion products may pass through tubes or piping in a heat exchanger, separate from heat exchanger 62, such that air directed by the blower 66 passes over the tubes or pipes and extracts heat from the combustion products. The heated air may then be routed from the furnace system 70 to the ductwork 68 for heating the residence 52.

FIG. 4 is an embodiment of a vapor compression system 72 that can be used in any of the systems described above. The vapor compression system 72 may circulate a refrigerant through a circuit starting with a compressor 74. The circuit may also include a condenser 76, an expansion valve(s) or device(s) 78, and an evaporator 80. The vapor compression system 72 may further include a control panel 82 that has an analog to digital (A/D) converter 84, a microprocessor 86, a non-volatile memory 88, and/or an interface board 90. The control panel 82 and its components may function to regulate operation of the vapor compression system 72 based on feedback from an operator, from sensors of the vapor compression system 72 that detect operating conditions, and so forth.

In some embodiments, the vapor compression system 72 may use one or more of a variable speed drive (VSDs) 92, a motor 94, the compressor 74, the condenser 76, the expansion valve or device 78, and/or the evaporator 80. The motor 94 may drive the compressor 74 and may be powered by the variable speed drive (VSD) 92. The VSD 92 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 94. In other embodiments, the motor 94 may be powered directly from an AC or direct current (DC) power source. The motor 94 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

The compressor 74 compresses a refrigerant vapor and delivers the vapor to the condenser 76 through a discharge passage. In some embodiments, the compressor 74 may be a centrifugal compressor. The refrigerant vapor delivered by the compressor 74 to the condenser 76 may transfer heat to a fluid passing across the condenser 76, such as ambient or environmental air 96. The refrigerant vapor may condense to a refrigerant liquid in the condenser 76 as a result of thermal heat transfer with the environmental air 96. The liquid refrigerant from the condenser 76 may flow through the expansion device 78 to the evaporator 80.

The liquid refrigerant delivered to the evaporator 80 may absorb heat from another air stream, such as a supply air stream 98 provided to the building 10 or the residence 52. For example, the supply air stream 98 may include ambient or environmental air, return air from a building, or a combination of the two. The liquid refrigerant in the evaporator 80 may undergo a phase change from the liquid refrigerant to a refrigerant vapor. In this manner, the evaporator 80 may reduce the temperature of the supply air stream 98 via thermal heat transfer with the refrigerant. Thereafter, the vapor refrigerant exits the evaporator 80 and returns to the compressor 74 by a suction line to complete the cycle.

In some embodiments, the vapor compression system 72 may further include a reheat coil in addition to the evaporator 80. For example, the reheat coil may be positioned downstream of the evaporator relative to the supply air stream 98 and may reheat the supply air stream 98 when the supply air stream 98 is overcooled to remove humidity from the supply air stream 98 before the supply air stream 98 is directed to the building 10 or the residence 52.

It should be appreciated that any of the features described herein may be incorporated with the HVAC unit 12, the residential heating and cooling system 50, or other HVAC systems. Additionally, while the features disclosed herein are described in the context of embodiments that directly heat and cool a supply air stream provided to a building or other load, embodiments of the present disclosure may be applicable to other HVAC systems as well. For example, the features described herein may be applied to mechanical cooling systems, free cooling systems, chiller systems, or other heat pump or refrigeration applications. Further, any of FIGS. 1-4 may include, in accordance with an aspect of the present disclosure, a fan reverse maintenance mode of an outdoor unit for an HVAC system, such as a split HVAC system. The fan reverse maintenance mode enables cleaning of a condenser coil of the outdoor unit, and in some embodiments a grille of the outdoor unit, which improves an efficiency of the HVAC system. In some embodiments, the fan reverse maintenance mode may be instructed in response to various data feedback inputs to a controller of the HVAC system. These and other features are described in detail below with reference to the drawings.

FIG. 5 is a cutaway perspective view of an embodiment of a stationary outdoor unit 100 of, for example, a climate management system such as a split HVAC system. The stationary outdoor unit 100 includes an enclosure 102. The illustrated enclosure 102 generally encloses an inner space 103 of the stationary outdoor unit 100, although the enclosure 102 may be configured to enable an air flow through one or more sides of the enclosure 102. For example, the enclosure 102 includes at least a first side 104, which may be referred to as a fan side or panel, and a second side 106, which may be referred to as a grille side or panel. Other sides of the enclosure 102 also operate to enclose the inner space 103. The second side 106, or grille side, of the enclosure 102 includes a grille 108 mounted therein. In some embodiments, multiple sides of the enclosure 102 may include a protective grille, and/or the grille 108 may extend along multiple sides of the enclosure 102. The grille 108 may be mounted over an air intake opening 109 of the enclosure 102. Further, the grille 108 may include, for example, a lattice structure or other structure configured to enable an air flow therethrough, but also to protect the inner space 103 and components therein from solids which cannot pass through the grille 108. In other words, the structure of the grille 108 allows air to pass therethrough, while blocking certain solids from passing therethrough.

The first side 104, or fan side, of the enclosure 102 includes a fan 110 therein. In some embodiments, the fan 110 may be partially disposed within the inner space 103 of the stationary outdoor unit 100. A compressor 112 and a heat exchanger, in this case a condenser coil 114, may also be disposed in the inner space 103 of the illustrated enclosure 102. The condenser coil 114 is disposed adjacent to the grille 108 and configured to receive an air flow thereover. The condenser coil 114 may include fins extending between segments of the condenser coil 114, which may enhance heat transfer. The compressor 112 is configured to receive a refrigerant, to compress the refrigerant, and to direct the refrigerant to the condenser coil 114. During a normal operating mode, fan blades of the fan 110 are rotated in a first circumferential operating direction 116 to draw air from an external environment 118 in which the stationary outdoor unit 100 is disposed, through the structure of the grille 108, over the condenser coil 114, through the inner space 103, through the fan 110, and back into the external environment 118. The air extracts heat from the compressed refrigerant flowing through the condenser coil 114, thereby cooling the refrigerant. The heat is then rejected to the external environment 118 via the air flow through the fan 110. In certain embodiments, the cooled refrigerant is then routed to an indoor unit which may include an expansion device and an evaporator coil.

As air is drawn from the external environment 118 across the grille 108 and the condenser coil 114, contaminants such as grass, dirt, dust, and other particulates in the air flow may gather or accumulate on the condenser coil 114 and, in some embodiments, the grille 108, which reduces an efficiency of the stationary outdoor unit 100 and corresponding HVAC system. That is, the contaminants may cause partially block the air flow, which reduces an efficiency of the stationary outdoor unit 100 and corresponding HVAC system. FIG. 6 is a cutaway perspective view of the stationary outdoor unit 100 of FIG. 5 in a fan reverse maintenance mode, which is configured to reduce or negate an effect of the above-described contaminants accumulated on the condenser coil 114 and, in some embodiments, the grille 108. As previously described, the fan blades of the fan 110 are rotated in a first circumferential operating direction during a normal operating mode. When contaminants accumulate at least on the condenser coil 114, it may be desirable to reverse a direction of the fan blades of the fan 110 thereby blowing the contaminants off of the condenser coil 114.

For example, a controller (illustrated in later drawings) may instruct a fan motor of the fan 110 to rotate the fan blades in a second circumferential maintenance direction 120 opposite to the first circumferential operating direction 116. The fan blades of the fan 110 may be structured/oriented to facilitate both the normal operating mode and the fan reverse maintenance mode. When the fan blades of the fan 110 rotate in the second circumferential maintenance direction 120 during the fan reverse maintenance mode, the fan 110 may draw air from the external environment 118 through the fan 110, and may push the air through the inner space 103, across the condenser coil 114 and the grille 108, and back into the external environment 118. Thus, contaminants gathered on the condenser coil 114 and/or the grille 108 may be pushed off the condenser coil 114 and/or the grille 108. In doing so, the fan reverse maintenance mode cleans the grille 108 and a flow path therethrough. By cleaning the grille 108, air flow therethrough is improved, improving an efficiency of the fan 110 and corresponding stationary outdoor unit 100.

FIG. 7 is a schematic illustration of a climate management system 150, such as a split HVAC system, having two conditioning units, including the stationary outdoor unit 100 configured to operate with a normal operating mode and a fan reverse maintenance mode. The climate management system 150 in the illustrated embodiment also includes a stationary indoor unit 152 in fluid communication with the stationary outdoor unit 100. As described above with reference to FIGS. 5 and 6, the climate management system 150 is configured to direct refrigerant between the stationary outdoor unit 100 and the stationary indoor unit 152. The stationary outdoor unit 100 includes the grille 108, the fan 110, the compressor 112, and the condenser coil 114. The stationary outdoor unit 100 in the illustrated embodiment also includes a fan motor 154, an air sensor 156, and a scheduling device 158, which may be referred to as a clock. It should be noted that the air sensor 156 and/or the scheduling device 158, in certain embodiments, may be general HVAC components and may not be associated exclusively with the stationary outdoor unit 100.

The stationary indoor unit 152 of the climate management system 150 may include, among other components, a heat exchanger 159 having an expansion device 160 and an evaporator coil 162. The expansion device 160 of the stationary indoor unit 152 may receive the refrigerant from the condenser coil 114 of the stationary outdoor unit 100. The evaporator coil 162 may receive the refrigerant from the expansion device 160, after the expansion device 160 expands the refrigerant. An air flow may pass over the evaporator coil 162, where the refrigerant in the evaporator coil extracts heat from the air flow. Thus, the air flow may be delivered to an indoor space 163 being conditioned by the split HVAC system 50. The stationary indoor unit 152 may also include an air demand device 164 which monitors an air demand from the climate management system 150 to the indoor space 163. In some embodiments, the air demand device 164 may be, or may be associated with, a thermostat.

A controller 170 of the climate management system 150 may receive data feedback inputs from the air sensor 156, the scheduling device 158, the air demand device 164, or any combination thereof. The air sensor, the scheduling device 158, the air demand device 164, related monitoring components, and any combination thereof may be referred to as being a part of a monitoring system 165. It should be noted that the controller 170 may be a general controller of the climate management system 150, a specific outdoor unit controller, or a controller specific to the monitoring system 165. In the illustrated embodiment, the illustrated controller 170 is configured to control at least the fan motor 154 of the fan 110 of the stationary outdoor unit 100. For example, the controller 170 includes a processor 172 and a memory 174, where the memory 174 is configured to store instructions that, when executed by the processor 172, cause the controller 170 to instruct various actions. In the illustrated embodiment, the controller 170 may receive data feedback from the air sensor 156 indicating a pressure drop across, for example, the condenser coil 114, from the scheduling device 158 indicating a scheduled maintenance interval, from the air demand device 164 indicating an upcoming or current air demand from the climate management system 150, or any combination thereof. Based on analysis of the data feedback, the controller 170 may instruct the fan blades of the fan 110 to turn in a circumferential maintenance direction opposite to a circumferential operating direction.

As previously described, the circumferential maintenance direction is configured to cause air to be blown by the fan 110 from an inner space of the enclosure 102 of the outdoor unit 100, across the condenser coil 114 and the grille 108, and to an external environment. In general, the controller 170 may analyze the data feedback from the air sensor 156 to determine whether the above-described pressure drop has exceeded a pre-determined threshold pressure. Additionally or alternatively, the controller 180 may analyze the data feedback from the scheduling device 158 to determine whether a maintenance interval is currently scheduled. Additionally or alternatively, the controller 180 may analyze the data feedback from the air demand device to determine whether a current or upcoming operational demand precludes a desire to initiate the maintenance mode. These and other control features are described in detail below, with reference to FIGS. 8-12.

FIG. 8 is a flow diagram illustrating a process 200 for a fan reverse maintenance mode of a stationary outdoor unit of, for example, a split HVAC system. The process 200 optionally includes instructing (block 202) a fan motor to turn fan blades of a fan in a first circumferential operating direction, which corresponds to a normal operating mode of the split HVAC system. Step 202 is illustrated with a dashed-line box to denote that the step 202 corresponds to normal operation of the HVAC system, whereas subsequent steps in FIG. 8 correspond to the presently disclosed maintenance mode.

The process 200 also includes receiving (block 204) data feedback from a data monitoring system, and analyzing the data feedback to determine (block 206) whether the data feedback warrants a fan reverse maintenance mode. For example, as previously described, a monitoring system having one or more feedback devices may communicate the data feedback to a controller, which makes the above-described determination (block 206). The data feedback may be the aforementioned air sensor 156 configured to detect a pressure drop across, for example, a condenser coil of the stationary outdoor unit. If the controller analyzes the data feedback from the air sensor 156 and determines that the pressure drop exceeds a threshold amount, the controller may instruct (block 208) the fan motor to turn the fan blades of the fan in a second circumferential maintenance direction opposite to the first circumferential operating direction. As previously described, the second circumferential maintenance direction of the fan blades may cause the fan to blow air from an inner space of the stationary outdoor unit across the condenser coil of the stationary outdoor unit, thereby blowing contaminants/debris off the condenser coil.

In certain embodiments, the controller may receive data feedback from a different data feedback device than the air sensor 156 described above, such as the aforementioned scheduling device 158 or clock. The scheduling device 158 may monitor an operating schedule of the stationary outdoor unit or split HVAC system having the stationary outdoor unit. A maintenance interval may be included in the operating schedule. For example, the maintenance interval may be planned once every day, week, two weeks, month, or some other moment in time, and for a pre-determined amount of time, such as for ten seconds, thirty seconds, one minute, two minutes, ten minutes, or some other amount of time. The controller may analyze the data feedback indicative of the operating schedule, and may instruct (block 208) the motor to turn the fan blades of the fan in the second circumferential maintenance direction at the scheduled moment in time and for the scheduled period of time.

In certain embodiments, the controller may receive data feedback from a different data feedback device than those described above, such as the aforementioned air demand device 164. The air demand device 164 may be configured to monitor an air demand from the split HVAC system to the conditioned space, or a parameter indicative of the air demand. If maintenance of the stationary outdoor unit is desired, the controller may first analyze the data feedback from the air demand device 164 to determine whether an upcoming or current air demand is incompatible with the fan reverse maintenance mode. For example, the fan reverse maintenance mode may generally be conducted when the indoor unit of the split HVAC system is not being utilized in certain ways to provide conditioned air to the space being conditioned by the split HVAC system. When the indoor unit of the split HVAC system is being utilized in certain ways to provide the conditioned air to the space being conditioned by the split HVAC system, it may be desirable to avoid the fan reverse maintenance mode. Thus, the controller may determine whether an upcoming or current air demand is incompatible with the fan reverse maintenance mode. If there is no upcoming or current air demand which is incompatible with the fan reverse maintenance mode, the controller may instruct (block 208) the fan motor to turn fan blades of the fan in the second circumferential maintenance direction.

However, in some embodiments, the air demand data feedback may be analyzed by the controller in conjunction with other data feedback to determine whether the fan reverse maintenance mode is desired. For example, the scheduling device data feedback may be analyzed by the controller to determine whether the fan reverse maintenance mode is scheduled to occur, and the air demand data feedback may be analyzed by the controller to determine whether upcoming or current air demand precludes the fan reverse maintenance mode during the regularly scheduled maintenance period. Examples of processes in which the controller considers two or more different types of data feedback are described below. It should be noted that that the feedback devices 209 may represent any of various different types of data feedback devices that may be employed in the process 200 of FIG. 8 and the processes illustrated in FIGS. 9-12. Any combination of the feedback devices 209 and/or other related components may be referred to as a monitoring system in accordance with the present disclosure.

In FIGS. 9-12, each process includes a step 212, 222, 232, 242, respectively, corresponding to the step 202 illustrated in FIG. 8 and described above. That is, the steps 202, 212, 222, 232, 242 are illustrated with dashed-line boxes to denote normal operation of the HVAC system, whereas subsequent steps correspond to the presently disclosed maintenance mode. In FIG. 9, the controller receives (block 214) data feedback from the air sensor and from the scheduling device. The controller determines (block 216) whether the data feedback from the scheduling device warrants the fan reverse maintenance mode, and if it does, the controller instructs (block 218) the previously described fan reverse maintenance mode. If the data feedback from the scheduling device does not suggest a fan reverse maintenance mode, the controller determines (219) whether the data feedback from the air sensor warrants the fan reverse maintenance mode. If the data feedback indicative of the pressure drop across the condenser coil or grille does not exceed the predetermined threshold, the process is repeated at step 214. Otherwise, the controller instructs (block 218) the fan reverse maintenance mode. In another embodiment, the controller may first analyze the data feedback from the air sensor, and then the data feedback from the scheduling device.

FIG. 10 is a flow diagram illustrating a process 220 for a fan reverse maintenance mode of a stationary outdoor unit. In FIG. 10, the controller receives (block 224) data feedback from the scheduling device and the air demand device. The controller determines (block 226) whether the data feedback from the air demand device precludes the fan reverse maintenance mode. For example, as previously described, an upcoming or current air demand from an HVAC system having the stationary indoor unit may preclude initiation of the fan reverse maintenance mode, since the fan reverse maintenance mode may not be compatible (or may reduce an efficiency of) the normal operation of the HVAC system in fulfilling the air demand. If the controller determines that the data feedback from the air demand device indicates an upcoming or current air demand that precludes initiation of the fan reverse maintenance mode, the process 220 begins again at block 224. If the controller determines that the data feedback from the air demand device does not preclude initiation of the fan reverse maintenance mode, the controller may then determine (block 229) whether the data feedback from the scheduling device warrants the fan reverse maintenance mode. For example, the controller may determine whether a maintenance interval is scheduled. If the data feedback from the scheduling device does not indicate that a fan reverse maintenance mode is scheduled, the process 220 begins again at block 224. If the data feedback from the scheduling device indicates a maintenance interval, the controller may instruct (block 228) the fan motor to turn the fan blades of the fan in the second circumferential maintenance direction, as previously described. In another embodiment, the controller may first consider the data feedback from the scheduling device, and may then consider the data feedback from the air demand device.

FIG. 11 is a flow diagram illustrating a process 230 for a fan reverse maintenance mode of a stationary outdoor unit. In FIG. 11, the controller receives (block 234) data feedback from the air sensor and the air demand device. The controller determines (block 236) whether the data feedback from the air demand device precludes the fan reverse maintenance mode. For example, as previously described, an upcoming or current air demand from an HVAC system having the stationary indoor unit may preclude initiation of the fan reverse maintenance mode, since the fan reverse maintenance mode may not be compatible (or may reduce an efficiency of) the normal operation of the HVAC system in fulfilling the air demand. If the controller determines that the data feedback from the air demand device indicates an upcoming or current air demand that precludes initiation of the fan reverse maintenance mode, the process 230 begins again at block 234. If the controller determines that the data feedback from the air demand device does not preclude initiation of the fan reverse maintenance mode, the controller may then determine (block 239) whether the data feedback from the air sensor warrants the fan reverse maintenance mode. For example, the controller may determine whether the air sensor data feedback indicates that a pressure drop in the stationary outdoor unit exceeds a threshold, indicating that contaminants have aggregated in or along a condenser coil and/or grille of the stationary outdoor unit. If the data feedback from the air sensor does not indicate a fan reverse maintenance mode is appropriate, the process 230 begins again at block 234. If the data feedback from the air sensor indicates a maintenance interval is desired, the controller may instruct (block 238) the fan motor to turn the fan blades of the fan in the second circumferential maintenance direction, as previously described. In another embodiment, the controller may first consider the data feedback from the air sensor, and may then consider the data feedback from the air demand device.

FIG. 12 is a flow diagram illustrating a process 240 for a fan reverse maintenance mode of a stationary outdoor unit. In FIG. 12, the controller receives (block 244) data feedback from the air sensor, the scheduling device, and the air demand device. The controller determines (block 246) whether the data feedback from the air demand device precludes the fan reverse maintenance mode. For example, as previously described, an upcoming or current air demand from an HVAC system having the stationary indoor unit may preclude a desire to initiate the fan reverse maintenance mode, since the fan reverse maintenance mode may not be compatible (or may reduce an efficiency of) the normal operation of the HVAC system in fulfilling the air demand. If the controller determines that the data feedback from the air demand device indicates an upcoming or current air demand that precludes a desire to initiate the fan reverse maintenance mode, the process 240 begins again at block 244.

If the controller determines that the data feedback from the air demand device does not preclude a desire to initiate the fan reverse maintenance mode, the controller may then determine (block 247) whether the data feedback from the air sensor warrants the fan reverse maintenance mode. For example, the controller may determine whether the air sensor data feedback indicates that a pressure drop associated with the stationary outdoor unit exceeds a threshold, indicating that contaminants have aggregated in or along, for example, the condenser coil. If the data feedback from the air sensor indicates a fan reverse maintenance mode is desired, the controller may instruct (block 248) the fan motor to turn the fan blades of the fan in the second circumferential maintenance direction.

If the data feedback from the air sensor indicates a maintenance interval is not desired, the controller may determine (block 249) whether the data feedback from the scheduling device warrants the fan reverse maintenance mode. For example, as previously described, the scheduling device data feedback may indicate that a regularly scheduled maintenance interval is due. If the scheduling device data feedback indicates maintenance is due, the controller may instruct (block 248) the fan motor to turn the fan blades of the fan in the second circumferential maintenance direction. By including regularly scheduled maintenance intervals in addition to maintenance modes initiated in response to undesirable pressure drops, the system is protected against air sensor failure and/or schedule device failure. In other words, the system includes redundancy in the event of certain failure modes, such that the fan reverse maintenance mode can be initiated even when singular monitoring components fail.

Presently disclosed embodiments include a stationary outdoor unit of an HVAC system, for example a split HVAC system, where the fan of the stationary outdoor unit is reversible. In certain embodiments, the fan is reversed in response to data feedback indicating pressure drops within the system, regularly scheduled maintenance periods, and/or air demands from the HVAC system. By reversing the fan, the air flow of the outdoor unit is reversed. For example, in the fan reverse maintenance mode, a grille of the enclosure of the stationary outdoor unit enables air flow from the inner space of the enclosure, over a condenser coil of the stationary outdoor unit, through the grille, and to the external environment. The air flow cleans the condenser coil and, in some embodiments, the grille of contaminants/debris formed therein.

While only certain features and embodiments of the disclosure have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters including temperatures and pressures, mounting arrangements, use of materials, colors, orientations, etc., without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode of carrying out the disclosure, or those unrelated to enabling the claimed disclosure. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation. 

1. A climate management system, comprising: a conditioning unit; a reversible fan of the conditioning unit; an enclosure of the conditioning unit separating an inner space of the enclosure from an external environment while allowing air flow therethrough, wherein the reversible fan comprises fan blades configured to be turned by a fan motor in a first circumferential direction so as to pull air from the external environment into the inner space of the enclosure; a monitoring system configured to monitor operational characteristics of the climate management system, and to communicate data feedback corresponding to the operational characteristics; and a controller configured to receive the data feedback from the monitoring system, and to instruct, based on analysis of the data feedback, the fan motor to turn the fan blades of the reversible fan in a second circumferential direction opposite to the first circumferential direction so as to push air from the inner space into the external environment.
 2. The climate management system of claim 1, wherein the enclosure comprises an air intake opening and a grille disposed in the air intake opening, and wherein the grille is configured to permit the air flow to travel through the air intake opening.
 3. The climate management system of claim 1, wherein the conditioning unit comprises a stationary outdoor unit.
 4. The climate management system of claim 3, wherein the stationary outdoor unit comprises a condenser coil disposed in the inner space, and wherein the condenser coil is configured to receive a refrigerant.
 5. The climate management system of claim 4, wherein the stationary outdoor unit comprises a compressor disposed upstream from the condenser coil, wherein the compressor is configured to compress the refrigerant prior to the condenser coil receiving the refrigerant.
 6. The climate management system of claim 4, comprising a stationary indoor unit configured to receive the refrigerant from the condenser coil of the stationary outdoor unit.
 7. The climate management system of claim 6, wherein the stationary indoor unit comprises an expansion device and an evaporator coil, wherein the expansion device is configured to receive the refrigerant from the condenser coil of the stationary outdoor unit and to expand the refrigerant, and wherein the evaporator coil is configured to receive the refrigerant from the expansion device.
 8. The climate management system of claim 1, wherein the monitoring system comprises an air sensor configured to monitor the operational characteristics of the climate management system relating to a pressure drop across or adjacent to an air intake opening of the enclosure.
 9. The climate management system of claim 1, wherein the monitoring system comprises an air demand device configured to monitor the operational characteristics of the climate management system relating to an upcoming or current operating air demand from the climate management system.
 10. The climate management system of claim 1, wherein the monitoring system comprises a schedule monitoring device configured to monitor the operational characteristics of the climate management system relating to a timed maintenance interval of the conditioning unit.
 11. The climate management system of claim 1, wherein the monitoring system comprises: an air sensor configured to monitor the operational characteristics of the climate management system relating to a pressure drop across or adjacent to an air intake opening of the enclosure; and an air demand device configured to monitor the operational characteristics of the climate management system relating to an upcoming or current operating air demand from the climate management system.
 12. The climate management system of claim 1, wherein the monitoring system comprises: an air sensor configured to monitor the operational characteristics of the climate management system relating to a pressure drop across or adjacent to an air intake opening of the enclosure; and a schedule monitoring device configured to monitor the operational characteristics of the climate management system relating to a timed maintenance interval of the conditioning unit.
 13. The climate management system of claim 1, wherein the monitoring system comprises: an air demand device configured to monitor the operational characteristics of the climate management system relating to an upcoming or current operating air demand from the climate management system; and a schedule monitoring device configured to monitor the operational characteristics of the climate management system relating to a timed maintenance interval of the conditioning unit.
 14. The climate management system of claim 1, wherein the monitoring system comprises: an air sensor configured to monitor the operational characteristics of the climate management system relating to a pressure drop across or adjacent to an air intake opening of the enclosure; an air demand device configured to monitor the operational characteristics of the climate management system relating to an upcoming or current operating air demand from the climate management system; and a schedule monitoring device configured to monitor the operational characteristics of the climate management system relating to a timed maintenance interval of the conditioning unit.
 15. A control system of a climate management system, the control system comprising: a monitoring system configured to monitor operational characteristics of the climate management system, and to communicate data feedback corresponding to the operational characteristics; and a controller configured to receive the data feedback from the monitoring system, and to instruct, based on analysis of the data feedback, a fan motor to turn fan blades of a reversible fan of a conditioning unit of the climate management system in a circumferential maintenance direction opposite to a circumferential operating direction so as to push air from an inner space within an enclosure of the conditioning unit into an external environment surrounding the enclosure.
 16. The control system of claim 15, wherein the monitoring system comprises an air sensor configured to monitor the operational characteristics of the climate management system relating to a pressure drop across or adjacent to an air intake opening of the enclosure.
 17. The control system of claim 15, wherein the monitoring system comprises an air demand device configured to monitor the operational characteristics of the climate management system relating to an upcoming or current operating air demand from the climate management system.
 18. The control system of claim 15, wherein the monitoring system comprises a schedule monitoring device configured to monitor the operational characteristics of the climate management system relating to a timed maintenance interval.
 19. The control system of claim 15, wherein the monitoring system comprises: an air sensor configured to monitor the operational characteristics of the climate management system relating to a pressure drop across an air intake opening of the enclosure; and an air demand device configured to monitor the operational characteristics of the climate management system relating to an upcoming or current operating air demand from the climate management system.
 20. The control system of claim 15, wherein the monitoring system comprises: an air sensor configured to monitor the operational characteristics of the climate management system relating to a pressure drop across or adjacent to an air intake opening of the enclosure; and a schedule monitoring device configured to monitor the operational characteristics of the climate management system relating to a timed maintenance interval of the conditioning unit.
 21. The control system of claim 15, wherein the monitoring system comprises: an air demand device configured to monitor the operational characteristics of the climate management system relating to an upcoming or current operating air demand from the climate management system; and a schedule monitoring device configured to monitor the operational characteristics of the climate management system relating to a timed maintenance interval of the conditioning unit.
 22. The control system of claim 15, wherein the monitoring system comprises: an air sensor configured to monitor the operational characteristics of the climate management system relating to a pressure drop across or adjacent to an air intake opening of the enclosure; an air demand device configured to monitor the operational characteristics of the climate management system relating to an upcoming or current operating air demand from the climate management system; and a schedule monitoring device configured to monitor the operational characteristics of the climate management system relating to a timed maintenance interval of the conditioning unit.
 23. A stationary outdoor unit of a heating, ventilation, and air conditioning (HVAC) system, the stationary outdoor unit comprising: a reversible fan having fan blades configured to be turned by a fan motor in a circumferential operating direction and in a circumferential maintenance direction opposite to the circumferential operating direction; an enclosure separating an inner space of the enclosure from an external environment while allowing air flow therethrough; a monitoring system configured to monitor operational characteristics of the HVAC system, and to communicate data feedback corresponding to the operational characteristics; and a controller configured to receive the data feedback from the monitoring system, and to instruct, based on an analysis of the data feedback, the fan motor to turn the fan blades of the reversible fan in the circumferential maintenance direction so as to push air from the inner space into the external environment.
 24. The stationary outdoor unit of claim 23, wherein the enclosure comprises an air intake opening and a grille disposed in the air intake opening, and wherein the grille is configured to permit the air flow to travel through the air intake opening.
 25. The stationary outdoor unit of claim 23, wherein monitoring system comprises an air sensor configured to monitor the operational characteristics of the HVAC system relating to a pressure drop across or adjacent to an air intake opening of the enclosure.
 26. The stationary outdoor unit of claim 23, wherein the monitoring system comprises an air demand device configured to monitor the operational characteristics of the HVAC system relating to an upcoming or current operating air demand from the HVAC system.
 27. The stationary outdoor unit of claim 23, wherein the monitoring system comprises a schedule monitoring device configured to monitor the operational characteristics of the HVAC system relating to a timed maintenance interval. 